In my experience, companies don't restrict contributions to 401ks as much as they used to. Many are now allowing a higher percentage to be invested monthly as well as allowing a person to invest from day 1, even if the match does not start for one year.

My company recently bumped their allowed amount from 20% to 50% and they have always (at least since I have worked here) allowed a person to invest in the 401k from the start. Our 5% match does not start for one year.